Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

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5: minutes

Problem 6

Textbook Question

Propose a mechanism for the acid-catalyzed reaction of cyclohexanone with pyrrolidine.

Verified step by step guidance

Identify the reaction type: This is an acid-catalyzed reaction between a ketone (cyclohexanone) and a secondary amine (pyrrolidine). Such reactions typically form an imine or an enamine through a condensation mechanism.

Step 1: Protonation of the carbonyl group. The acid catalyst donates a proton to the oxygen atom of the carbonyl group in cyclohexanone, increasing the electrophilicity of the carbonyl carbon. This makes it more susceptible to nucleophilic attack.

Step 2: Nucleophilic attack by pyrrolidine. The nitrogen atom in pyrrolidine, which has a lone pair of electrons, attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate.

Step 3: Proton transfer and elimination of water. A proton transfer occurs within the intermediate, followed by the elimination of a water molecule. This step forms a positively charged iminium ion intermediate.

Step 4: Deprotonation to form the final product. The iminium ion loses a proton, resulting in the formation of the enamine product. The acid catalyst is regenerated in this step, completing the catalytic cycle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In these reactions, the acid donates a proton (H+) to a reactant, enhancing its electrophilicity and facilitating nucleophilic attack. Understanding the role of the acid is crucial for predicting the reaction pathway and the stability of intermediates formed during the process.

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically in a carbonyl group. In the case of cyclohexanone, the carbonyl carbon is susceptible to attack by nucleophiles like pyrrolidine, leading to the formation of an intermediate. This step is essential for understanding how the reaction proceeds and the nature of the products formed.

Mechanistic Pathways

Mechanistic pathways describe the step-by-step sequence of elementary reactions that occur during a chemical transformation. For the reaction of cyclohexanone with pyrrolidine, outlining the mechanistic steps, including protonation, nucleophilic attack, and subsequent deprotonation, is vital for predicting the final product and understanding the reaction's overall dynamics. This knowledge helps in visualizing how reactants convert into products.

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